The translation of several physiologic sensor technologies from acute laboratory use to chronic implantable use has been hampered to a large degree by chronic drift due to the accumulation of biological material over the sensor. For example, pressure sensors are mounted on catheters with a diaphragm protecting the strain gage element from the blood pool. Acute thrombus formation or long-term fibrotic growth alters the coupling between the blood pressure and the diaphragm deformation, causing a loss in the fidelity of the pressure measurement.
Optical sensors measure reflectance and absorbance of specific wavelengths by the blood to determine the hematocrit, oxygen saturation or glucose levels. Acute thrombus formation or long-term fibrotic growth attenuates some of the emitted light, causing an erroneous measurement.
There is a need in the art for a system that recalibrates sensors in vivo to account for the accumulation of biological material over the sensor when implanted chronically. There is also a need in the art for a method of recalibrating chronically implanted sensors in vivo.